What is Association and referencing environment?
Association: binding identifiers to particular data objects and subprograms Referencing environment: the set of identifier associations for a given subprogram. Referencing operations during program execution: determine the particular data object or subprogram associated with an identifier.
What do you mean by referencing environment of subprogram?
ANS: LOCAL REFERENCING ENVIRONMENTS Subprograms are generally allowed to define their own variables, thereby defining local referencing environments. Variables that are defined inside subprograms are called local variables because access to them is usually restricted to the subprogram in which they are defined.
What are the design issues of subprograms?
Some of the design issues of subprogram are: Are local variables static or dynamic? Can subprogram definitions appear in other subprogram definitions? What parameter-passing method or methods are used? Are the types of the actual parameters checked against the types of the formal parameters?
What is a subprogram header?
A subprogram header is the first line of the definition, serves several definitions: It specifies that the following syntactic unit is a subprogram definition of some particular kind. The header provides a name for the subprogram. May optionally specify a list of parameters.
What is local referencing environment?
Local Referencing Environments. Local referencing environments are the simplest structures and consist of the various identifiers declared in the head of a subprogram (variable names, formal parameter names, and subprogram names).
What is purpose CIP and CEP?
Current Instruction Pointer (CIP): The pointer which points to the instruction in the code segment that is currently being executed (or just about to be) by the hardware or software interpreter. Current Environment Pointer (CEP): Each activation record contains its set of local variables.
How many types of subprograms are there in basic?
Two fundamental kinds
Two fundamental kinds of subprograms are procedures and functions.
What are generic subprograms?
A generic subprograms is a subprogram which have parametric polymorphism. A generic subprogram can accept different types of values of same single memory location. Parametrically polymorphic subprograms are often called generic subprograms. C++ provide a kind of compile-time parametric polymorphism.
What is coroutines in PPL?
What is coroutine? Answer = Coroutine is a function that allows pausing its own execution and resuming from the exact same point after a condition is met.
What are types of sequence control?
Sequence control structures can be either explicit or implicit. Implicit sequence control structures are those represented by the language and explicit are those that the programmer may optionally use. Data control structures may be categorized according to the referencing environment of data.
How do you define subprogram?
A subprogram is defined as a set of statements that can be reused at multiple places in a program when convenient. This reuse results in multiple types of savings, from memory space to coding time.
Why are subprograms used?
Subprograms also provide modularity; that is, they let you break a program down into manageable, well-defined logic modules. This supports top-down design and the stepwise refinement approach to problem solving. Also, subprograms promote reusability and maintainability.
What are the benefits of subprograms?
Benefits of using subprograms
- Subprograms are usually small in size, which means they are easier to write, test and debug than programs.
- Subprograms can be saved separately as modules and used again in other programs.
- A subprogram may be used repeatedly at various points in the main program.
What are coroutines and subroutines?
The difference between coroutine and subroutine is : Unlike subroutines, coroutines have many entry points for suspending and resuming execution. Coroutine can suspend its execution and transfer control to other coroutine and can resume again execution from the point it left off.
What is sequence control in PLC?
Sequential control, also known as “step control”, it controls the device in a pre-determined order.
What is control and sequencing used for?
Sequence control refers to user actions and computer logic that initiate, interrupt, or terminate transactions. Sequence control governs the transition from one transaction to the next.
What is an example of a subprogram?
computer programming language …is an example of a subprogram (also called a procedure, subroutine, or function). A subprogram is like a sauce recipe given once and used as part of many other recipes. Subprograms take inputs (the quantity needed) and produce results (the sauce).
How do subprograms work?
Subprograms are small programs that are written within a larger, main program. The purpose of a subprogram is to perform a specific task. This task may need to be done more than once at various points in the main program.
What is the referencing environment of a statement?
The referencing environment of a statement is the collection of all names that are visible in the statement In a static scoped language, that is the local variables plus all of the visible variables in all of the enclosing scopes (see ex., p. 184) A subprogram is active if its execution has begun but has not yet terminated
What are the different types of reference environments?
Referencing environments may be local, nonlocal, global, or predefined. The reference environment of a statement is the collection of all names that are visible in the statement. Referencing environments are generally invariant during program execution, i.e., values may change but name associations do not.
What is the referencing environment in dynamic programming languages?
In a dynamic-scoped language, the referencing environment is the local variables plus all visible variables in all active subprograms (see ex., p. 185)
What is the referencing environment of a subprogram?
A subprogram is active if its execution has begun but has not yet terminated In a dynamic-scoped language, the referencing environment is the local variables plus all visible variables in all active subprograms (see ex., p. 185)